Heads question

[hotrod_991]

Ok I am working on getting a better set of allum heads after advise from several awesome rodders. Now I have another question

64 or 74cc's? which is better what what diffrence does it make? I will hold of on buying till I know. Thank you kindly

[softballnrd27]

Depends on what pistons you have and what comp ratio you want

[hotrod_991]

so higher cc makes higher CR? i have SRP .040 2 valve relief pistons

[Keller]

no, it's the opposite. smaller cc's create more compression.

[Stubnosebrock]

Sounds like you just have a flat top piston. Id go with the 64's for what you want. Compression is good on a naturally aspirated high performance engine, but you have to be careful, unless you want to run race fuel. The good news is with aluminum heads, you can get away with a little more compression, and still be pump gas friendly. 91/93 octane of course.

[hotrod_991]

Originally Posted by Stubnosebrock

Sounds like you just have a flat top piston. Id go with the 64's for what you want. Compression is good on a naturally aspirated high performance engine, but you have to be careful, unless you want to run race fuel. The good news is with aluminum heads, you can get away with a little more compression, and still be pump gas friendly. 91/93 octane of course.

thank you for helping clear that up. I will go with the 64's, and all I have ever ran in it is 91 and octane booster. Except a few tight wallet days had use lil cheaper lol

[Stubnosebrock]

Depending on what head gasket you use, id guess you will be around 10 to 1 compression. give or take a little. If you look around and find some info on your pistons, most manufacturers will tell you what compression they're pistons will make with what CC head your looking at. But that is what i would use, and you would have a pretty good street engine.

[hotrod_991]

Thanks I am tryn to track down some of the older steel GM head gaskets cause they were alittle thinner from what my dad was telling me.

[hotrod_991]

So i was searching my local CL and say a complete fresh 383 with and engine dyno sheet that has never been stabbed for 1700 so was thinking about maybe selling what I have and buying that complete if I can find anyone that is interested in mine. might be the cheaper route to get to were I want to be. Will see tho I do enjoy building my own stuff.

[Marv D]

You don't need to search for the old GM 0.020" steel shim gaskets,, Felpro #1094 is 0.015" nominal after compression. With a standard .0.025" normal undecked block, you will have a 0.040" quench. As good as it get's without milling the block.

edit
DOH, never mind, your looking at aluminum heads,, that won't work

[hotrod_991]

Originally Posted by Marv D

You don't need to search for the old GM 0.020" steel shim gaskets,, Felpro #1094 is 0.015" nominal after compression. With a standard .0.025" normal undecked block, you will have a 0.040" quench. As good as it get's without milling the block.

edit
DOH, never mind, your looking at aluminum heads,, that won't work

its all cool MarvD still usefull information to have about the quench. I priced everything to do what I want to the motor. roller set up, complete heads, intake mani, and 750 carb and a new Comp cam tourqe convertor all came out to about 3200, so at the crossroads now.

[Stubnosebrock]

If your looking at buying the whole engine, do yourself the big favor, and make sure the guy has receipts. Thats pretty cheap for a motor that has good work done to it. If your gonna buy a whole new deal, make sure it has a good rotating assembly. Im sure you dont want to do this a whole bunch more. Your gonna want some good power to move that heavy truck as fast as you want, and the bottom end has to be able to handle it, or else your new engine wont be worth much.

[hotrod_991]

yea i really dont want to be in the same boat with a diffrent motor Iether it was jsut an idea. Most likely will just build the one I have a little more. gonna work from the top down. the AFR 195 heads, cam ect. later I will change out the crank to something alittle lighter than the cast, and my harmonic balancer bolt wont stay in the crank end due to it being stripped out.

[Rannos]

I may just be paranoid but I have never liked the idea of buying a built motor from anyone other then a known shop. Even then I want to take my motor to them and have it built. I always start thinking " If this motor so is good why are they selling it?". Then add in the added expense of machine work for a 383 and I would think that much more on why is it so cheap? Hope which ever way you go works out for ya.

Even buying a used motor to build I would rather it be a complete motor no one has ever been into, but like I said I'm paranoid.

[leftcoast66]

Originally Posted by Rannos

I may just be paranoid but I have never liked the idea of buying a built motor from anyone other then a known shop. Even then I want to take my motor to them and have it built. I always start thinking " If this motor so is good why are they selling it?". Then add in the added expense of machine work for a 383 and I would think that much more on why is it so cheap? Hope which ever way you go works out for ya.

Even buying a used motor to build I would rather it be a complete motor no one has ever been into, but like I said I'm paranoid.

Glad to hear I'm not alone, I feel the same way. Too many variables on tolerances and how it was built and preparation.

I'm very interested in your build though, I've got an all forged 350 with factory big valve heads on. I'm looking at what's next for power (it was built on a shoestring budget while I was in high school).

[hotrod_991]

yea i figure I will just put the money into mine and built it personally. Better to stop tryn to cut corners and just fork over the cash to do it right lol. I will have alittle progress on it early next year when I get my two weeks of leave. Right now wife just starts it once a week lets it warm up then shuts it off till next week.